•4 


hxcmangp: 


JUN 


1919 


WAR  DEAFNESS  AND  ITS 

PREVENTION -REPORT    OF    THE 

LABYRINTHS  OF  THE  ANIMALS 

USED  IN  TESTING  OF 

PREVENTIVE  MEASURES. 

(MIDDLE  EARS  PREVIOUSLY 

REPORTED) 


BY 

STACY  R.  GUILD 

From  the  Department  of  Anatomy,  University  of  Michigan 
Medical  School,  Ann  Arbor,  Michigan 


A  Dissertation  Submitted  in  Partial  Fulfillment  of 

the  Requirements  for  the  Degree  of  Doctor  of 

Philosophy  in  the  University  of  Michigan 


Reprint    from 

THE  JOURNAL  OF 

LABORATORY  AND  CLINICAL  MEDICINE 

St.  Louis 


Vol.  IV,  No.  4,  January,  1919 


■/ 


WAR  DEAFNESS   AND  ITS   PREVENTION— REPORT  OF  THE  LABY- 
RINTHS OF  THE  ANIMALS  USED   IN  TESTING  OF  PREVENTIVE 
MEASURES*    (MIDDLE  EARS  PREVIOUSLY  REPORTED)! 


By  Stacy  R.  Guild,  Ann  Arbor,  Mich. 


METHODS 

A  FULL  description  of  the  procedure  by  which  each  animal  was  handled  at 
the  time  of  exposure  to  the  detonations  was  given  in  the  report  of  the 
middle  ear  conditions;  reference  may  be  made  to  it  for  that  part  of  the  technic. 
In  that  report  the  protective  measures  tested  were  also  listed  and  described. 
As  stated  there  the  animals  were  killed  about  48  hours  after  exposure  to  the 
detonations.  The  treatment  of  the  tissues  at  the  time  of  killing  the  animals 
was  directed  primarily  to  the  securing  of  the  best  possible  cochlear  fixation. 
The  method  used  was  the  one  with  which  I  had  had  the  best  results  in  a  series 
of  experiments  on  cochlear  histologic  technic,  conducted  as  a  preliminary  to 
objective  work  on  the  physiology  of  hearing  w^hich  the  war  has  postponed  in- 
definitely, but  which  I  hope  at  some  future  time  to  carry  out.  The  fixation 
fluid  used  was  Zenker- formol  in  the  proportions  suggested  by  Maximow  (1909), 
as  a  modification  of  Kelly's  fluid,  for  other  work.  A  stock  solution  is  made  in 
the  following  proportions : 

Mercuric  bichloride,  50  gm. 

Potassium  dichromate,  25  gm. 

Sodium  sulphate,  10  gm. 

Distilled  water,  1000  c.c. 

This  was  filtered  carefully  to  exclude  any  particles  which  might  block 
small  vessels.  Just  before  using  there  was  added  to  this  stock  solution  10  per 
cent  by  volume  of  10  per  cent  formalin;  the  glacial  acetic  acid  of  the  regular 
Zenker's  fluid  was  not  added.  Both  solutions  were  kept  in  an  oven  at  39  ■  C. 
until  the  time  of  mixing  for  use.  The  fixative  was  injected  through  the  vascular 
system,  following  a  thorough  washing  out  with  a  0.75  per  cent  solution  of 
sodium  chloride,  also  kept  at  39°  C.  until  placed  in  tlie  flask  for  injection.  This 
preliminary  washing  out  is  essential  for  the  securing  of  good  penetration  of  the 
fixative. 


*Submitted  to  the  National   Research  Council. 

From   the   Department   of   Anatomy,    l^niversity   of    Michigan    Medical    School,    Ann   Arbor,    Michigan. 

tThree  previous  reports  have  been  made;  the  first  was  published  in  this  Journal.  September, 
1917;  the  second,  January,  1918;  and  the  third,  ^Iarch,  1918.  The  second  report  is  the  one  containing  the 
account   of   the   middle   ears   the   labyrinths   of   which   are   here   reported. 


392638 


The  routing  prucJL-Uyic  ^wii  j4>.  jyiace   the  animal   under  chloroform  anes- 
thesia ;  then  to  open  the  thorax  and  j^ericardial  sac  and  insert  the  cannula  of 
the  injecting  apparatus  in  the  systemic  aorta  through  the  wall  of  the  left  ven- 
tricle, the  ligature  heing  placed  hy  passing  the  thread  through  the  transverse 
sinus  of  the  pericardium,  thus  including  the  pulmonary  aorta.     This  can  be  done 
very  rapidly  after  a  few  trials  and  I  was  able  regularly  to  have  the  saline  solu- 
tion running  soon  enough  to  avoid  any  clotting  of  blood  in  the  cochlear  vessels. 
The  vessels  to  the  caudal  half  of  the  body  were  routinely  clamped  off  by  a  hemo- 
stat  placed  so  as  to  include  both  aorta  and  inferior  vena  cava  just  above  the 
diaphragm.     This  reduced  the  amounl  of  fluid  necessary  for  satisfactory  injec- 
tion of  the  cochlear  region.     The  injection  was  made  with  air  jiressurc  averag- 
ing 145  mm.  of  mercury.     About   150  c.c.  of  warm  saline  srjiution  were  used 
in  washing  out  the  blood  and  this  was  followed  immediately  by  200  c.c.  of  the 
warm  fixative  described  above.     Only  a  small  portion  of  this  reaches  the  coch- 
leae, of  course,  since  all  the  blood  vessels  of  the  upper  half  of  the  body  are  in- 
jected.    The  cochleae  and  some  of  the  surrounding  bone,  including  most  of  the 
vestibular  parts,   were  then  removed   and   the  two  pieces  placed   in   50  c.c.   of 
<\arm  fixing  fluid  and  left  at   room  temperature.     These   remained   in  the  fix- 
ing fluid  from  a  week  to  ten  days,  the  fluid  being  changed  two  or  three  times, 
because  a  precipitate   forms  slowly  after  mixing  the  formalin  with  the  Zenker 
stock  solution.     They  were  then  washed  for  24  hours  in  running  tap  water  and 
placed  in  10  per  cent  alcohol ;  and  were  transferred  from  this  to  80  per  cent 
alcohol  by  10  per  cent  changes  at  24  hour  intervals.     They  were  then  placed  in 
80  per  cent  alcohol  to  which  had  been  added  a  sufficient  amount  of  a  saturated 
solution  of  iodine  in  absolute  alcohol  to  make  the  mixture  a  clierrv  red  color. 
In  this  they  remained  until  they  ceased  to  decolorize  the  solution,  more  iodine 
being  added  as  needed,     'i'his  time  averaged  about  ten  days.     They  were  then 
passed  at  24  hour  intervals  through  90  per  cent  and  95  per  cent  alcohol  into 
absolute  alcohol  which  was  changed  three  times.     Instead  of  passing  them  di- 
rectly into  the  mixture  of  equal  parts  of  absolute  alcohol  and  ether,  they  were 
passed    through    four    intermediate    mixtures,    each    increasing   the    ether    ratio 
10  per  cent  until  the  50  per  cent  was  reached.     This  was  an  extra  precaution  to 
avoid  as  far  as  possible  shrinkages  due  to  a  more  sudden  change.     Ordinarv 
celloidin  embedding  followed,  slow  evaporation  being  used,  taking  a  month  or 
more  to  reach  a  firm  consistency.    The  blocks  were  then  hardened  in  80  per  cent 
alcohol  and  transferred  through  50  per  cent  and  30  per  cent  alcohols  into  4  per 
cent  nitric  acid  for  decalcification.     They  remained  in  this  12  days,  except  two 
groups,  one  of  which  remained  6  days  and  the  other  9  days.     The  fluid  was 
changed  daily.     They  were  then  transferred  to  a  5  i)er  cent  solution  of  sodium 
sulphate,  remaining  in  this  48  hours  with  one  change  of  fluid;  and  were  then 
washed  in  running  tap  water  for  24  hours.     The  blocks  were  then  "double  em- 
bedded" in  paraffin.     They  were  passed  from  the  tap  water  through  30.  50,  80, 
and  95  per  cent  alcohols,  and  the  dehydration  completed  with  carbol-xylol  (crys- 
tal carbolic  acid  one  part,  xylol  three  parts).     Aksolute  alcohol  can  not  be  used 


because  of  the  celloidin  present.  An  intermediate  step  of  equal  parts  oi  95  per 
cent  alcoliol  and  carbol-xylol  was  used  to  make  the  change  more  graduah  After 
dehydration  with  carbol-xylol  they  were  changed  to  xykjl  and  while  thus  cleared 
the  blocks  were  trimmed  in  such  a  way  that  the  position  of  the  modiolar  axis 
could  be  determined  later  for  orientation  of  the  sectioning.  They  were  in- 
filtrated and  embedded  in  52°  C.  paraffin  in  the  usual  way,  the  celloidin  block 
containing  the  cochlea  being  handled  as  a  piece  of  tissue. 

This  method  gave  in  most  cases  a  very  fair  preservation  of  the  delicate 
epithelial  structures  in  the  cochlea ;  in  a  few  instances  it  has  failed,  these  are 
probably  cases  where  the  vascular  injection  did  not  penetrate  well.  The  pres- 
ervation of  the  tectorial  membrane  is  poor  by  this  method,  it  is  usually  found 
curled  back  in  part  of  the  turns,  and  it  is  not  so  thick  as  some  methods  show 
it  to  be. 

From  blocks  prepared  by  this  method  it  is  possible  to  cut  thinner  serial 
sections  than  have  usually  been  employed  in  studies  on  the  cochlea.  From  such 
a  block  I  have  an  unbroken  series  of  5  micra  sections  of  a  whole  guinea  pig 
cochlea,  and  I  have  cut  some  at  3  micra,  but  not  a  series.  The  material  used 
in  this  study  is  cut  in  7  micra  sections;  because  of  the  shortage  of  glassware, 
especially  of  large  cover-glasses,  only  every  fifth  section  was  saved.  It  would 
have  been  impossible  to  mount  all  the  series  otherwise.  From  the  wide  extent 
of  the  injured  areas  reported  in  the  experiments  of  Wittmaack,  Yoshii,  and 
others,  it  was  thought  that  every  fifth  section  would  be  sufficient  to  fully  indi- 
cate the  extent  of  the  injuries.  For  an  exact  study  of  the  distribution  of  injury 
that  I  have  found  unbroken  series  are  needed ;  every  fifth  section  gives  the 
general  distribution  of  injured  areas,  but  the  study  of  unbroken  series  might 
yield  additional  facts  of  interest.  The  sectioning  was  done  with  a  sliding  micro- 
tome, using  the  "water-on-the-knife"  method.  The  blocks  were  oriented  so  as 
to  parallel  the  modiolus  as  nearly  as  possible  in  sectioning;  in  most  cases  this 
was  closely  approximated,  in  a  few  there  was  some  deviation.  In^  mo5tt<sbIocks 
the  sectioning  was  continued  until  the  stapes  was  reached ;  in  s^pif  j^J^  was  Mirced 
to  stop  sooner  either  because  of  imperfect  decalcification  of  t^iS.  BlI)(^'\Di/  be- 
cause of  hard  particles  in  the  niche  of  the  round  windgvy^  (^r  el-Sewhere^^  this 
region ;  these  particles  are  probably  grains  of  sand  from  fhe-tap-wsfrer,  which 
was  unusually  laden  with  dirt  at  the  time  part  of  the  washing  was  done.  The 
sections  were  fixed  to  slides  by  the  usual  water-albumen  paraffin  section  method, 
and  were  stained  with  Heidenhain's  iron  lac  hematoxylin ;  counterstained  with 
benzopurpurin,  and  mounted  in  damar.  The  technic  differed  from  the  usual 
treatment  of  paraffin  sections  on  slides  only  in  the  use  of  carbol-xylol,  instead 
of  absolute  alcohol,  in  passing  from  xylol  to  95  per  cent  alcohol  and  back  again. 
This  was  necessary  because  of  the  celloidin  present.  To  completely  remove 
mercuric  crystals  the  sections  were  passed  through  an  iodine  solution  in  80  per 
cent  alcohol  before  the  transference  to  iron  alum.  The  benzopurpurin  was  used 
in  solution  in  95  per  cent  alcohol ;  the  sections  permitted  to  overstain,  and  the 
excess  stain  removed  by  fresh  95  per  cent  alcohol ;  the  slides  being  transferred  to 
carbol-xylol   to   stop  the  decolorization  at   the  desired   stage. 


RESULTS 

The  condition  oi  tlic  lain  rintliinc  parts,  here  reported,  should  he  compared 
with  the  middle  ear  conchtions,  previously  reported ;  this  can  readily  be  done 
for  the  individual  cars,  as  the  animal  designation  has  been  made  in  all  tabulations. 

The  injuries  to  the  inner  car  have  been,  for  the  most  part  at  least,  limited 
to  the  cochlea.  In  no  case  were  all  of  the  special  sensory  areas  in  the  vestibular 
part  of  the  labyrinth  sectioned,  owing  to  the  close  trimming  of  the  blocks 
neces.sary  to  save  glassware.  Of  those  sectioned,  many  of  the  macul.c 
acusiicae  and  some  of  the  crista;  acustica?  have  some  shrunken  hair  cells,  but 
I  have  no  reason  to  believe  that  these  are  more  than  artefacts.  The  stapes 
was  reached  in  the  sectioning  in  76  of  the  92  cochleae  cut ;  of  the  76,  all  but 
10  are  in  the  normal  position.  In  each  of  these  ten  cases  the  annular  ligament 
is  broken  and  the  base  plate  of  the  stapes  tilted  more  or  less  into  the  vesti- 
bule. While  this  condition  may  be  due  to  the  detonations,  I  am  inclined  to 
believe  that  it  was  caused  by  accidents  in  handling  at  some  time  before  the 
celloidin  embedding,  most  probably  during  the  removal  from  the  animal. 
Therefore  these  displacements  will  not  be  considered  further.  In  both  ears 
of  one  animal  no  joint  cavity  is  present  about  the  base  plate  of  the  stapes,  but 
this  is  not  a  condition  which  can  be  attributed  to  the  detonation.  The  position 
of  the  membrana  tympani  secundaria,  closing  the  fenestra  rotunda,  is  normal,  or 
nearly  so,  in  all  cases;  it  is  slightly  wavy  in  some,  but  no  more  so  than  the 
changing  fluids  might  account  for.  In  part  of  the  membranes  there  is  some 
edema  evident,  especially  of  the  middle  ear  surface.  Free  blood  cells  and  clots 
are  present  on  the  middle  ear  surface,  but  these  are  the  result  of  the  damage  to 
the  middle  ear  parts,  already  considered.  None  of  the  labyrinths  have  what 
may  be  called  "gross"  lesions,  such  as  the  rupture  of  the  walls  of  the  ductus 
cochlearis  or  the  .scala  vestibuli  or  the  scala  tympani.  The  occasional  bending 
of  parts  of  the  basilar  membrane  occurs  as  often  in  controls  as  in  exposed  ani- 
mals, and  is  probably  due  to  the  eml)edding.  Definite  lesions  of  the  organ  of 
Corti  and  of  the  spiral  ganglion  arc  present  in  many  of  the  cochleie.  Xo  evi- 
dence of  extensive  internal  hemorrhage  was  found  in  any  of  the  labyrinths ; 
in  .some  a  few  isolated  blood  cells  were  observed  adhering  to  the  scala  tympani 
surface  of  the  basilar  membrane.     (See  Figs.  10  and  13.) 

To  present  the  appearance  of  the  lesions  ob.served  drawings  will  be  used ; 
they  are  selected  to  show  the  more  usual  types  of  injuries. 

In  speaking  of  the  turns  of  the  cochlea  the  method  of  designating  by  half- 
turns,  beginning  at  the  basal  end,  has  been  selected  as  best  adapted  to  the  pur- 
poses of  this  report.  Fig.  1  shows  in  outline  a  modiolar  section  with  the  turns 
numbered  according  to  the  method  used.  The  part  in  the  midmodiolar  section 
is  considered  as  the  middle  of  each  half-turn;  the  junctions  of  the  half-turns 
have  the  organ  of  Corti  cut  tangentially.  Such  junctions  may  be  .seen  in  Fig. 
2.  In  speaking  of  sections  of  the  organ  of  Corti  the  term  "radial"  refers  to 
those  in  the  region  of  the  modiolar  sections;  the  term  "tangential"  refers  to 
sections   in  the  region  of  the  junction   of   two   half-turns;   the  term   "oblique" 


refers  to  sections  in  the  intermediate  region.  Fig.  3  is  of  a  normal  organ  of 
Corti  in  radial  section,  Fig.  4  is  of  a  nornixil  organ  in  oblique  section,  and  Fig.  12 
is  of  a  normal  organ  in  tangential  section.  The  ohlif|ue  and  tangential  sections 
are  favorable  for  the  observing  of  certain  of  the  lesions  because  several  of 
each  element  of  the  organ  of  Corti  are  included  in  each  section.  The  first 
part  of  the  first  half-turn  which  deviates  from  the  axis  of  the  cochlear  s])iral 
and  is  almost  parallel  to  the  modiolus  for  a  distance  in  the  vestibule,  has  been 
listed  separately  in  the  records  made;  it  is  termed  the  "vestibular  part";  Fig. 
2  shows  the  relation  of  this  part  of  the  ductus  cochlearis  to  the  rest  of  the 
labyrinth.  The  fenestra  rotunda  is  "beneath"  the  last  portion  of  the  vestib- 
ular part. 

Figs.  3  to  14,  inclusive,  are  at  the  same  magnification- — 295  diameters;  they 
are  therefore  directly  comparable,  and  are  at  a  magnification  sufficient  to  permit 
ready  recognition  of  parts.  The  normal  sections  are  inserted  for  comparison 
with  the  injured  ones. 

The  loss  of  single  or  of  a  few  adjacent  outer  hair  cells  is  the  definite  injury 
of  most  frequent  occurrence  and  is  evidently  the  least  severe  of  the  definite 
lesions.  Figs.  6,  7,  8,  and  13  show  sections  having  such  lesions  in  radial, 
oblique,  and  tangential  sections.  Special  features  in  the  various  sections  are 
mentioned  in  the  legends  (q.v.).  Such  loss  of  hair  cells  is  usually  associated 
with  a  displacement  of  the  corresponding  Deiters'  cells,  frequently  showing  as 
a  nuclear  displacement,  as  in  Fig.  7.  Derangements  of  Deiters'  cells  without 
loss  of  hair  cells  have  not  been  called  injuries  in  the  records  made  for  the  reason 
that  they  may  possibly  be  artefacts.  For  some  time  I  w'as  not  certain  that  the 
absence  of  isolated  hair  cells  indicated  an  injury,  but  after  finding  such  gaps 
in  many  of  the  best  preserved  cochlese  I  have  arrived  at  the  conclusion  that 
these  are  not  artefacts.  This  belief  is  further  strengthened  by  the  increasing 
frequency  of  such  absences  as  an  area  of  more  severe  injury  is  approached 
in  following  the  organ  of  Corti  in  serial  sections.  As  may  be  seen  in  the  illustra- 
tions given  it  is  possible  to  have  several  degrees  of  severity  of  such  injuries, 
depending  on  the  proportion  of  outer  hair  cells  which  are  missing.  It  ranges 
from  the  loss  of  a  single  cell  in  one  section  with  all  the  other  sections  of  the 
region  normal,  up  to  the  loss  of  the  majority  of  the  cells  in  all  sections  for  a 
considerable  distance.  All  these  various  lesions  I  have  grouped  under  the  term 
of  first  degree  injury,  which  may  be  defined  as  the  loss  of  part  of  the  outer 
hair  cells  with  or  without  derangement  of  the  Deiters'  cells. 

The  absence  of  all  the  outer  hair  cells  is  the  condition  found  next  in  order 
of  frequency  to  the  preceding.  Fig.  8  illustrates  this  lesion.  This  condition  may 
be  present  in  all  the  sections  of  a  half-turn  or  more;  it  ranges  from  this  large 
extent  to  a  single  section.  Since  only  every  fifth  section  has  been  saved,  the 
presence  of  this  condition  in  a  single  section  of  a  series  means  that  it  may  have 
extended  over  any  or  all  of  the  four  sections  to  either  side  which  were  not  saved. 
It  will  be  noted  in  the  illustration  that  the  organ  of  Corti  retains  its  general 
outline;  this  is  one  of  the  differentiating  points  between  this  injury  and  the 
more  severe  types.     This  condition,  absence  of  all  outer  hair  cells  with  retention 


of  the  general  shape  of  the  organ  of  Corti,  lias  been  termed  second  degree  injury, 
for  purposes  of  reference. 

Of  less  frequent  occurrence  than  the  preceding  condition  is  that  illustrated 
in  Fig.  9.  Not  only  are  the  outer  hair  cells  missing  but  also  the  organ  of  Corti 
is  crushed  out  of  shape;  the  illustration  shows  the  usual  condition  of  the  tilling 
of  the  tunnncl,  Xuel's  space,  and  the  outer  tunnel  space  with  cellular  debris. 
In  some  cases  there  is  more  or  less  vacuolization  of  the  mass.  It  will  be  observed 
that  the  inner  hair  cell  is  present,  as  it  is  in  the  other  lesions  so  far  described. 
This  condition  does  not,  in  my  material,  occur  in  isolated  sections,  but  areas  so 
injured  are  always  adjacent  at  one  end,  and  usually  at  both,  to  areas  of  lesser 
or  of  greater  injury.  This  condition,  absence  of  outer  hair  cells  associated 
with  a  general  crushing  of  the  organ  of  Corti  with  massed  or  vacuolizcd  debris 
in  the  large  spaces  of  the  organ,  has  been  termed  third  degree  injury. 

A  more  severe  lesion  of  the  organ  of  Corti  is  that  illustrated  in  Figs.  10 
and  14.  In  this  lesion  the  outer  hair  cells  are  all  absent,  the  organ  of  Corti 
is  badly  broken  up,  the  cellular  debris  is  usually  vacuolized  but  may  be  massed 
as  in  the  typical  third  degree  injur}-,  and  the  inner  hair  cell  is  absent.  The 
cells  of  the  internal  spiral  sulcus  are  frequently  vacuolized.  This  condition 
has  been  termed  fourth  degree  injury,  and  is  characterized  by  the  severe  dis- 
integration of  the  organ  of  Corti  with  absence  of  the  inner  hair  cell,  which 
is,  of  the  special  sensory  epithelial  cells,  the  least  often  missing.  In  only  one 
instance  was  the  inner  hair  cell  observed  in  an  abnormal  condition  when  the 
rest  of  the  organ  of  Corti  in  that  section  was  normal.  Two  adjacent  sections 
of  a  series  (every  fifth  section  saved)  show  a  chromatolysis  of  the  inner  hair 
cell.  In  one  of  these  two  sections  there  is  no  other  injury  evident;  the  other 
section  has  part  of  the  outer  hair  cells  missing.  Elsewhere  definite  lesions  of 
the  inner  hair  cells  have  been  obsen^ed  only  in  association  with  severe  injuries 
to  the  rest  of  the  organ  of  Corti.  This  fourth  degree  injur)-,  like  the  third  de- 
gree, is  not  found  in  isolated  sections  in  otherwise  normal  areas,  but  areas  of 
it  are  bounded  by  areas  of  lesser  degree  of  injury. 

Fit,'.  1 1  sh(nvs  the  most  complete  destruction  of  the  organ  of  Corti  which 
is  present  in  my  material;  it  occurred  in  a  zone  of  fourth  degree  iniury, 
and  since  it  occurred  but  once  I  have  not  given  it  a  special  designation  of  degree. 

The  distribution  of  the  lesions  of  the  organ  of  Corti  in  the  various  cochlene 
studied  is  shown  in  the  charts  of  Plate  IV.  In  making  these  charts  the  relative 
lengths  of  the  various,  half-turns  have  lieen  approximated,  instead  of  show- 
ing each  half-turn  as  of  the  same  value.  To  indicate  the  various  degrees  of 
injur}-  three  shades  of  grey,  parallel  lines,  and  dots  have  been  used.  The 
darkest  shade  of  grey  represents  the  condition  that  has  been  termed  fourth 
degree  injur}-;  the  intermediate  grey,  third  degree  injury;  and  the  light  grev. 
second  degree  injury.  The  narrowest  of  these  light  grey  zones  represent  single 
sections,  though  they  are  proportionately  t<M)  wide  for  the  actual  ratio  which 
a  single  section  ^^hnuld  cover  in  tlic  chart.  The  parallel  lines  indicate  areas 
where  all  sections  are  in  the  condition  termed  first  degree  injury;  and  the 
dots   indicate   first   degree   injury   in   isolated    sections.      Where   two   or   three 


adjacent  sections  are  in  this  condition  it  has  been  shown  by  drawing  a  Hne 
underneath  the  dots,  unless  it  is  between  zones  of  more  severe  injury,  in  which 
case  parallel  lines  have  been  used.  The  number  of  dots  is  not,  in  most  cases, 
the  exact  number  of  sections  with  lesions  but  the  number  of  dots  indicates  the 
relative  frequency  of  sections  showing  injury  to  the  organ  of  Corti.  Since 
only  every  fifth  section  has  been  saved,  the  absolute  distribution  can  not  be  de- 
termined from  these  series.  The  position  of  the  ends  of  the  injured  areas 
can  be  determined  only  by  means  of  graphic  reconstruction  which  allows  for 
the  difference  in  length  of  the  part  of  the  organ  of  Corti  contained  in  radial, 
oblique,  and  tangential  sections.  I  have  devised  a  suitable  method  for  making 
such  graphic  reconstructions,  but  have  not  used  it  here  since  most  of  its  value 
over  the  method  of  approximation  would  be  lost  due  to  having  only  every  fifth 
section.  In  studying  the  cochlese  the  organ  of  Corti  and  other  structures  were 
followed  section  by  section  from  the  vestibular  end  of  the  cochlear  duct  to 
the  apical  end,  being  traced  back  and  forth  through  each  series  for  the  dif- 
ferent turns.  The  notes,  from  which  the  charts  presented  were  made,  were 
jotted  down  at  the  time  of  observing  injured  areas  during  these  examinations 
of  series. 

For  convenience  of  reference,  the  conditions  recorded  have  been  grouped 
in  four  charts. 

In  Chart  I  are  placed  all  cases  wdiere  the  outer  ear  was  entirely  open  and 
the  detonation  used  was  one  shot  from  a  45  caliber  Colt  automatic  pistol  with 
the  muzzle  at  15  cm.  from  the  ear.  Most  of  these  are  the  open  ears  of  animals 
in  which  the  other  ear  was  "protected;"  in  all  cases  the  15  cm.  was  measured 
from  the  opposite  ear,  and  the  barrel  pointed  downwards  about  20  degrees 
along  the  left  side  from  above  and  in  front. 

In  Chart  II  are  presented  the  controls  with  the  open  rubber  ear  and  glass 
tubes  of  various  sizes.  From  a  study  of  the  great  variations  in  individual 
cases  in  the  cochleae  recorded  in  Chart  I,  where  all  were  exposed  to  as  similar 
traumatic  conditions  as  possible,  it  is  evident  that  the  number  of  controls  with 
each  tube  is  too  small,  there  being  only  one  with  each,  except  with  the  2  mm. 
tube,  and  in  this  case  the  extra  two  animals  were  used  because  wax  entered  the 
end  of  the  tube  during  the  experiment   (cf.  middle  ear  observations). 

In  Chart  III  are  presented  the  conditions  of  the  cochleae  of  the  "protected" 
ears.  To  facilitate  comparison,  these  have  been  arranged  in  the  same  order  as 
the  middle  ear  observations  on  the  protected  ears   (q.v.). 

In  Chart  IV  are  presented  the  conditions  of  the  cochleae  of  animals  sub- 
mitted to  detonations  other  than  the  usual  one  shot  at  15  cm. 

Besides  these,  two  animals  were  taken  as  controls  of  the  possible  injury 
to  the  ears  while  in  the  basket  during  the  experiment  with  others.  One  of 
these,  animal  62,  was  also  placed  in  ihe  holding  apparatus  as  a  control  of  pos- 
sible injuries  by  this  procedure.  The  other,  animal  63,  simply  remained  in 
the  basket  during  six  experiments,  being  exposed  thus  to  the  sound  of  six  shots 
from  the  pistol  at  a  distance  of  about  25  feet,  the  gun  pointing  away  from  the 


basket.  Both  cochleie  of  animal  62  are  entirely  normal.  The  left  cochlea 
of  animal  63  has  a  few  sections  with  missing  or  distorted  outer  hair  cells  in 
the  sixth  half-turn;  the  right  cochlea  has  ab<nit  30  isolated  sections  with  some 
outer  hair  cells  missing,  scattered  throughout  its  length  except  in  the  vestibular 
part  and  the  eighth  half-turn;  the  injured  sections  are  most  numerous  in  the 
third  to  the  sixth  half-turns. 

Shrinkage  and  chromatolysis  of  i)art  of  the  cells  in  parts  of  the  si)iral 
ganglion  are  present  in  many  of  the  cochleae;  this  condition  is  present  most 
often  in  the  vestibular  part  and  lir.^t  half-turn;  less  frequently  it  is  present 
in  the  second,  third  and  fourth  half-turns,  and  occurs  very  seldom  alx)ve  this 
level.  In  general  the  distribution  corresponds  with  the  injuries  to  the  organ 
of  Corti.  but  there  are  many  exceptions  to  this  general  arrangement.  In  the 
vestibular  part  and  first  half -turn  shrujiken  ganglion  cells  are  much  more  fre- 
quently j)rescnt  in  the  cochleae  of  unprotected  ears  than  the  protected  ones  in 
which  definite  lesions  of  the  organ  of  Corti  occurred;  and  in  these  unpro- 
tected ears  the  number  of  shrunken  ganglion  cells  frequently  appears  to  be  a 
much  greater  proportion  of  all  the  cells  than  the  proportion  of  hair  cells  miss- 
ing in  the  corresi)onding  region.  On  the  other  hand,  in  many  cases  the  ganglion 
cells  show  no  injury  in  regions  corresponding  to  parts  of  the  organ  of  Corti 
that  were  severely  injured.  The  possibility  must  always  be  kept  in  mind  that 
these  ganglion  cell  alterations  may  be  artefacts;  but  after  observing  many  cases 
where  the  occurrence  of  a  zone  of  injury  corresponds  to  a  zone  of  ganglion 
cell  shrinkage  and  protoplasmic  change  I  am  of  the  oj)inion  that  these  in- 
dicate a  true  lesion.  Animals  allowed  to  live  a  longer  period  of  time  after 
being  submitted  to  detonations  are  needed  to  definitely  settle  this  point.  In 
two  cases  all  the  ganglion  cells  were  in  bad  condition,  but  in  both  of  these 
the  general  fixation  w-as  so  poor  that  the  alteration  is  in  all  probability  an  arte- 
fact. In  a  few  cases  some  of  the  nerve  fibers  leading  from  the  ganglitw  to  the 
organ  of  Corti  are  definitely  degenerating;  in  most  cases  they  appear  nearly, 
if  not  entirely,  normal.  The  fibers  in  the  organ  of  Corti  itself  can  not  be 
seen  in  the  sections  of  the  more  severe  lesions. 

A  peculiar  condition  is  present  in  the  cochleae  of  animal  44.  The  ductus 
cochlearis,  sacculus,  and  utriculus  are  distended  to  an  unusual  size.  Reissner's 
membrane  is  bulged  into  the  scala  vestibuli  and  is  longer  than  normal.  It  is 
not  thickened.  The  walls  of  the  utriculus  and  sacculus  are  similarly  dis- 
tended. The  distention  is  somewhat  less  in  the  right  cochlea.  The  right 
cochlea  of  animal  37  has  a  similar,  but  much  less  distended,  condition  from 
the  basal  end  to  the  fifth  half-turn,  and  the  second  and  third  half-turns  of 
animal  27  show  it  in  slight  degree.  In  the  one  wiiii  the  greatest  distention, 
the  left  cochlea  of  animal  44,  the  stria  vascularis  of  most  of  the  third  half- 
turn  and  of  part  of  the  first  half -turn  has  a  peculiar  enlargement  of  the  blood 
vessels.  The  enlargement  of  the  blood  vessels  of  the  stria  vascularis  and  the 
distention  of  the  endolymphatic  channels  of  the  left  cochlea  of  animal  44  may 

8 


be  associated  as  cause  and  effect  but  it  seems  doubtful  in  view  of  the  facts 
that  enlarged  vessels  are  not  present  in  the  other  cases  of  distention  and  that 
several  cases  of  enlarged  vessels,  though  of  much  less  extent,  are  present  in 
cochlcc-e  where  no  distention  has  occurred.  I  wish  to  specifically  state  that  I 
am  undecided  whether  either  the  enlargement  of  the  vessels  of  the  stria  vas- 
cularis or  the  distention  of  the  endolymphatic  channels  has  been  caused  by  the 
detonations. 

DISCUSSION    OF    RESULTS 

In  discussing  the  above  observations  upon  the  labyrinths  their  bearing 
upon  the  relative  efficiency  of  the  various  protective  measures  will  be  con- 
sidered first  and  the  evidence  from  the  three  sets  of  observations  which  I 
have  made  correlated.  Then  a  comparison  will  be  made  of  the  lesions  in  my 
material  with  those  recorded  by  other  observers  upon  detonation  injuries  of 
the  labyrinth,  and  the  bearing  of  the  results  upon  the  general  problem  of  the 
physiology  of  hearing  indicated. 

I.  Relative  Efficiency  of  Protective  Measures. — The  condition  of  the  mid- 
dle ear  parts  and  the  tambour  results,  reported  previously,  both  indicated  a  di- 
vision of  the  protective  m.easures  into  two  distinct  groups  on  the  basis  of 
their  relative  efficiency  in  preventing  the  passage  of  the  force  of  the  detonation 
waves  used;  these  two  sets  of  results  agree  in  the  devices  which  would  be  placed 
in  each  group.  Drv^  cotton,  the  Elliott  protector,  and  the  Wilson-Michelson 
instruments  are  in  the  less  efficient  group.  Examination  of  Chart  III  shows 
that  the  division  into  groups  on  the  basis  of  the  cochlear  results  is  not  so 
well  marked;  each  of  the  protective  measures  failed  to  prevent  definite  coch- 
lear lesions  in  one  or  more  of  the  ears  with  which  it  was  used.  Even  here, 
however,  a  ranking  of  the  devices  is  evident;  and  two  of  the  three  protective 
measures  Avhich  are  in  the  less  efficient  group  on  the  basis  of  the  other  tests 
again  rank  lowest. 

It  may  be  that  one  of  the  groups  of  observations  is  of  more  value  than  the 
others ;  if  so,  this  should  receive  the  most  consideration  in  drawing  conclusions. 
I  would  call  attention  to  the  fact  that  the  animal  experiments  are  the  ones 
Avhich  indicate  the  devices  that  permit  an  injurious  amount  of  detonation  waves 
to  pass;  the  physical  experiments  are  of  value  in  helping  to  place  the  preven- 
tives in  their  relative  order  of  efficiency.  The  tambour  method,  on  the  other 
band,  has  the  advantage  which  all  experiments  in  physics  have  over  biologic 
work;  i.  e.,  the  materials  used  are  not  subject  to  the  individual  variations  which 
the  reactions  of  living  organisms  are.  It  is  evident  from  the  great  variations 
in  the  cochlear  injury  in  the  cases  where  the  ear  was  open  and  the  conditions 
were  as  similar  as  possible  that  there  is  either  a  great  individual  difference  in 
guinea  pigs  in  the  degree  of  susceptibility  to  injury  of  this  type  or  an  entirely 
unrecognized  factor  acting  to  modify  the  detonations  (see  Chart  I).  In  the 
conduction  of  the  animal  experiments  with  protective  measures  there  are  oppor- 
tunities for  errors  in  technic ;  they  were  recognized  and  guarded  against,  but 
the  possibilitv  must  be  kept  in  mind  that  in  some  cases  the  wax  packing  used 
may  not  have  completely  prevented  the  entry  of  injurious   force  through   the 


crevices  around  the  tube  which  it  was  supposed  to  close,  or  that  the  device 
may  not  have  been  properly  jilaccd  in  the  rubber  ear.  The  foniier  error 
is  the  more  probable ;  the  latter  is  one  that  is  more  likely  to  occur  in  the 
use  of  devices  by  troops  than  under  laboratory  conditions.  If  it  were  not  for 
the  great  individual  diflferences  in  the  long  series  of  controls  (Chart  I),  I 
would  be  inclined  to  think  that  the  possible  errors  mentioned  alx)ve  had  oc- 
curred often,  and  that  therefore  the  cochlear  results  were  almost  worthless 
as  a  basis  for  comparison  of  the  relative  efficiency  of  the  devices.  But,  if 
such  were  the  case,  the  (|uestion  immediately  arises  as  to  why  the  middle  ears 
were  not  also  damaged  in  a  like  ratio.  As  a  possible  exi)lanation  of  the 
discrepancy  here  might  be  advanced  the  general  belief  for  many  years  among 
otologists  that  in  cases  of  air  wave  trauma  of  the  ear  the  injury  to  the  laby- 
rinth is  less  when  the  tympanic  membrane  ruptures  than  when  it  remains 
intact;  the  explanation  advanced  is  that  the  force  is  expended  in  ru])turing 
the  tympanic  membrane.  The  statements  are  based  upon  clinical  experience. 
Yoshii  (1909)  reported  one  animal  which  has  a  bearing  upon  the  subject.  In 
this  case  a  guinea  pig  was  exposed  to  the  detonation  from  the  firing  of  a  re- 
volver at  20  cm.  (size  of  gun  and  j^sition  witli  reference  to  the  animal  not 
given).  At  autopsy  it  was  found  that  the  right  middle  ear  was  l)adly  damaged 
while  the  left  middle  ear  was  entirely  normal.  Study  of  the  cochlere  showed 
the  right  one  to  be  entirely  normal,  while  the  left  one  showed  "very  light  de- 
gree alteration."  From  his  description  the  alteration  is  less  than  anything  T 
have  called  a  definite  lesion.  This  case  agrees  with  the  clinical  view.  In  my 
material,  animals  17  and  18  were  the  only  ones  in  which,  under  similar  con- 
ditions for  the  two  ears,  one  tympanic  membrane  remained  intact  and  the 
other  ruptured.  In  animal  17  the  cochlea  of  tl>e  side  with  the  normal  middle 
ear  was  severely  injured,  while  the  other  cochlea  was  only  slightly  injured. 
In  animal  18  difficulties  in  technic  prevent  any  definite  statement  as  to  the 
cochleae.  Since  the  tympanic  membrane  was  rui^ured  in  all  cases  of  oj)en  ears 
exposed  to  the  usual  detonation,  no  comparison  is  jxissible  in  this  series.  How- 
ever, there  are  many  cases  here,  and  in  the  controls  with  the  open  rubber  ear 
and  glass  tube,  in  which  the  cochlea  was  severely  injured.  Of  the  ears  with 
which  dr>-  cotton,  the  Elliott  protector,  and  the  Wilson-Michelson  instrument 
were  used,  all  had  damaged  middle  ear  parts ;  one  of  each  group  of  three  had 
the  tympanic  membrane  ruptured,  though  less  severely  than  in  most  of  the  cases 
of  open  ears.  With  dry  cotton,  the  cochlea  of  the  ear  with  a  radial  slit  in  the 
tympanic  membrane  is  definitely  injured;  the  injury  to  this  cochlea  is  greater 
than  to  one  of  the  other  two,  and  less  than  the  injury  to  the  third  one.  \\  ith 
the  Elliott  protector  the  cochlear  injury  is  nnich  less  in  the  case  with  a  rup- 
tured tympanic  membrane  thati  in  the  two  where  it  remained  intact.  W  ith 
the  \\  ilson-Michelson  device  the  c(»chlear  injur)'  in  the  case  of  the  ruptured 
tympanic  membrane  is  about  the  same  as  in  one  of  the  other  two  and  less 
than  the  injury-  in  the  third  ca^e.  With  the  rest  of  my  material  such  com- 
parisons can  not  be  properly  made,  because  the  force  of  the  detonation  waves 
reaching  the  ears  varied  greatly,  due   either  to  different  protectors  or  to  dif- 

10 


ferent  distances  used.  While  some  of  my  cases  are  in  accordance  with  the 
idea  that  rupturing  of  the  tympanic  tends  to  protect  the  labyrinth,  it  seems  to 
me,  on  the  whole,  that  the  exceptions  to  the  rule  are  too  numerous  to  accept 
it  as  an  explanation  of  the  inconsistency  between  the  middle  car  and  the  coch- 
lear conditions.  In  this  my  material  agrees  with  the  clinical  experience  of 
Meyer  with  troops  submitted  to  modern  battlefield  conditions.  It  seems  im- 
probable that  a  true  "bone  conduction"  can  have  played  much,  if  any,  part 
here,  since  the  vibrations  would  have  had  to  pass  through  a  person's  body  to 
reach  the  ground  on  which  the  anim.al  rested. 

The  condition  of  the  cochleae  of  animal  63,  used  as  a  control  for  pos- 
sible injury  while  in  the  stock  basket  during  the  testing  with  other  animals 
(see  page  7),  was  a  surprise  to  me,  as  I  fully  expected  this  control  to  be 
normal ;  animal  62  had  both  cochlea  entirely  nonnal.  There  is  a  possibility 
that  the  lesions  present,  outer  hair  cells  missing  in  isolated  sections,  are  not 
due  to  detonations,  in  w^hich  case  all  the  lesions  of  this  nature  would  have  to 
be  ruled  out  of  consideration.  On  the  other  hand,  if  they  are  due  to  the  de- 
tonations of  the  pistol  at  the  distance  at  which  the  basket  was  placed,  (25 
feet  with  the  gun  pointing  in  the  opposite  direction),  all  the  cases  of  such 
"isolated  section"  lesions  must  be  considered  as  possibly  due  to  such  an  origm 
and  their  bearing  on  the  protection  afforded  by  devices  thrown  out.  At  the 
time  of  the  experimentation  I  considered  the  distance  sufficient  to  avoid  any 
such  complication;  at  present  I  must  leave  the  question  of  interpretation  open. 
Here,  as  in  the  other  groups,  variation  has  occurred;  one  animal  normal  and 
one  injured    ( ?). 

As  the  most  suitable  way  of  determining  the  ranking  given  by  the  com- 
bined tests  to  the  protective  measures,  the  method  of  adding  the  rankings  given 
by  the  different  tests  has  been  chosen.  All  three  sets  of  observations  are  given 
the  same  value  by  this  method.  The  devices  tested  only  by  the  tambour  method 
are  omitted  in  this  tabulation.  To  determine  the  order  of  efficiency  as  given  by 
the  tambour  method  the  results  with  the  three  guns  used  are  ranked.  AMien 
two  devices  are  tied  for  a  place,  the  sum  of  this  and  the  next  lower  ranking 
is  halved  and  each  of  the  devices  given  this  number.     (See  Tables  I  and  II.) 

The  ranking  arrived  at  by  this  method  is  open  to  criticism,  and  is,  at  best, 
only  an  approximation.  The  division  into  two  groups  is  very  definite,  however; 
and  the  other  requirements  for  military  use  should  be  the  deciding  factor  in 
choosing  from  the  more  efficient  group,  rather  than  the  slight  differences  in 
the  laboratory  results  with  these  protective  measures.  These  other  factors 
have  already  been  considered  in  the  previous  reports  and  need  not  be  taken  up 
here.  It  suffices  to  state  that  the  "Tommy"  is  the  best  of  the  mechanical 
devices  from  the  standpoint  of  general  military  requirements  for  field  use  by 
troops,  and  since  it  has  a  slight  advantage  over  the  others  in  the  laboratory 
tests  it  is  the  protective  measure  which  seems  to  be  indicated  for  a  large  field 
trial.  On  the  other  hand,  the  results  of  the  laboratory  tests  seem  to  eliminate 
the  need  of  field  trials  by  troops  of  dry  cotton,  the  Elliott  protector,  and  the 
Wilson-Michelson  device. 

11 


II.  Comparison  with  Previous  Work  on  Detonation  Injuries. — The  extent 
and  distribution  of  the  injuries  to  the  organ  of  Corti  in  the  animals  I  have  used 
are  quite  different  from  those  reported  by  \\  ittmaack,  Yoshii,  and  Prenant 
and  Castex,  but  are  similar  to  some  of  Hoessli's  and  of  Hoshino's  cases.  \\  ith 
the  exception  of  some  of  Hoessli's  experiments  all  the  animals  used  1)v  other 
workers  have  been  exposed  to  detonations  with  the  ears  entirely  open.  W'itt- 
maack's  statements  are  very  indefinite  regarding  his  detonation  cases ;  some 
animals  were  negtitive,  and  no  statement  is  made  of  the  extent  of  the  injured 
area  in  the  ones  which  were  injured.  The  one  figure  which  he  presented  of 
a  detonation  injury  is  from  the  next  to  the  highest  turn   (fifth  and  sixth  half- 

Taule  I 
Ranki.ng  ok  the  Devices  by  tiik  Ta.mbour  Method 


RANKING  ACCORDING  TO 

SUMOE 
RANKINGS 

RESULTING 
RANKING 

PROTECTIVE  MEASl'RE 

22 
CALIBER 

38 

CALIBER 

44 

CALIBER 

Vaselined  cotton 
"Tommy" 
Glycerined  cotton 
Mallock-.\rmstrong 
Wax  cone 
Wilson-Michelson 
Elliott  Protector 
Dry  cotton 

1/2 
3 

VA 

4 
5 
8 
6 

7 

1 

4 

2/2 
5 
6 

7 
8 

2 
1 
3 

5 
4 
6 
7 
8 

4/2 
6/2 
8/. 

ll'/2 

14 
20 
20 
23 

1 
2 
3 

4 
5 
6/2 

8 

Table  II 
Ranking  of  Devices  by  the  Average  oe  the  Three  Sets  of  Results 


RANKING  ACCORDING  TO 

SUM  OF 
R.\NKINGS 

RESULTING 
RANKING 

PROTECTIVE  MEASURE 

TAMBOUR 

MIDDLE  EAR 

LABYRINTH 

METHOD 

CONDITIONS 

CONDITIONS 

"Tommy" 

2 

1 

4 

7 

1 

Mallock- .Armstrong 

4 

2 

3 

9 

2/2 

Glycerined  cotton 

3 

5 

1 

9 

2/2 

Wax  cone 

5 

3 

2 

10 

4 

Vaselined  cotton 

1 

4 

6 

11 

5 

Elliott  Protector 

6^ 

7 

7 

20'^ 

6/2 

Wilson-Michelson 

6J4 

6 

8 

20^ 

tY2 

Dry  cotton 

8 

8 

5 

21 

8 

turns  of  my  terminology)  ;  it  resembles  somewhat  the  lesion  I  have  tcnned 
third  degree  injury.  A  study  of  this  and  other  figures  given  by  Wittmaack 
leads  me  to  agree  with  the  group  of  workers  in  Siebenmann's  laboratory  at 
Basel ;  1.  e.,  there  are  many  artefacts  due  to  faulty  histologic  tcchnic  in  the 
work  of  Wittmaack,  so  that  even  his  indefinite  statements  must  bo  discounted. 
As  in  all  of  his  work  on  cochlear  injury  by  sound  waves  W  ittmaack  considered 
the  injury  to  the  ganglion  cells  the  primary  lesion  and  the  epithelial  degenera- 
tion secondary.  The  lesions  found  by  Yoshii  in  the  middle  ears  were  very 
similar  to  those  of  my  unprotected  animals.  The  two  figures  given  by  him 
of  the  organ  of  Corti  after  exposure  to  single  detonations  show  a  condition 
which  agrees  with  that  which   I   have  termed   fourth  degree  injury.    (An  ex- 


12 


tensive  quotation  from  Yoshii's  description  of  the  lesions  observed  by  him  was 
given  in  the  report  on  the  Hterature,  page  851  of  the  September,  1917,  Journal 
of  Laboratory  and  Clinical  Medicine,  to  which  the  reader  is  referred.)  He 
reported  this  severe  lesion  as  present  the  whole  length  of  the  cochlea,  which 
is  a  lesion  more  extensive  than  is  present  in  any  of  the  animals  I  have  used. 
He  also  reported  changes  in  the  ganglion  cells,  and  he,  like  the  rest  of  the 
Siebenmann  group  of  workers,  considered  these  to  be  secondary  degenera- 
tions and  the  epithelial  primary.  He  also  mentioned  hemorrhage  into  the  spaces 
of  the  labyrinth  in  some  cases.  The  size  of  the  gun  used  by  Yoshii  was  not 
definitely  stated;  he  merely  said,  "Diese  Versuche  wurden  teils  mit  einer  Kin- 
derpistole  und  blossen  Ziindhiitchen,  teils  mit  Revolver  und  Patronen  unmit- 
telbar  vor  der  Ohnnuschel  und  zwar  jeweilen  an  beiden  Ohren  rasch  nachein- 
ander  ausgeflihrt."  He  placed  the  muzzle  of  the  gun  much  closer  to  the  ear 
than  I  did,  and  in  reality  exposed  each  ear  to  two  detonations ;  for  my  experi- 
ments show  that  both  ears  are  damaged  at  much  greater  distances  than  that 
between  the  two  ears  of  the  guinea  pig.  This  closer  range  may  account  for 
the  more  extensive  injury  his  animals  received.  He  used  eight  animals  in  this 
series;  two  were  killed  immediately,  and  one  each  after  2,  3,  8,  25,  45,  and 
60  days  respectively.  In  view  of  my  results  it  seems  probable  that  more  an- 
imals might  have  given  him  more  variation.  In  any  case,  his  statements  as 
to  some  regeneration  having  occurred  in  the  animals  killed  after  the  longer 
intervals  certainly  needs  confirmation  with  a  greater  number  of  animals  for 
each  stage. 

Hoessli,  in  his  first  series  with  detonations,  was  testing  primarily  air  and 
bone  conduction,  to  determine  which  transmits  the  injurious  force.  He  used 
three  guinea  pigs  with  the  incus  removed  on  the  left  side  of  each,  and  two 
animals  with  moistened  cotton  in  both  ears.  All  were  placed  in  a  cage  and 
a  Swiss  army  revolver  was  fired  five  times  at  about  30  cm.  above  them.  They 
were  killed  24  hours  later.  Each  animal  was  reported  by  a  separate  proto- 
col. In  none  of  the  cases  was  there  any  damage  to  the  middle  ear  parts, 
other  than  the  operative  injury  in  the  animals  with  the  incus  removed.  All 
three  of  the  cochleae  in  the  cases  with  the  incus  removed  were  normal,  as 
were  also  three  of  the  four  ears  which  had  moistened  cotton  in  the  external 
meatus.  In  two  of  the  three  open  ears  with  normal  middle  ear  parts  and 
one  of  the  cotton  protected  ears  the  cochleae  had  lesions  in  the  organ  of 
Corti  in  the  lower  half  of  the  second  turn  (third  half-turn  of  my  termi- 
nolog}')-  The  injury  as  described  agrees  with  what  I  have  termed  third  degree 
injury ;  Hoessli  noted  that  the  inner  hair  cells  were  present,  and  stated  that 
there  was  no  evidence  of  injury  to  the  ganglion  cells  or  nerve  fibers,  except 
the  fibers  in  the  organ  of  Corti  itself.  Except  for  this  half-turn  he  reported 
the  cochleae  normal.  Of  the  third  case  of  open  ear  with  normal  conducting 
apparatus,  he  said:  ''Die  Scala  cochlcce  ist  im  ganzen  normal  und  zeigt  keine 
Veranderungen.  Einzig  an  derjenigen  Stelle,  wo  wir  in  Fall  22  die  ausge- 
dehnten  Veranderung  vorfinden,  sehen  wir  hier  einen  teilweisen  Mangel  der 
ausseren  Haarzellen  bei  sonst  normalen  Cort.  Organ.     Die  iibrigen  Skalateile 

13 


sind  chcnfalls  normal."  Apparently  this  was  a  slij^lil  injury;  l^lfjcs^li  was 
properly  very  cautious  as  to  the  interpretation  of  possible  artefacts.  In  those 
of  Hoessli's  cases  which  are  comparable  to  mine,  cochlear  injuries  occurred 
in  the  same  region  where  mine  show  the  most  frequent  injury;  i.e.,  the  third 
half-tuni.  The  cf)ndition  of  the  unprotected  middle  ear  parts  in  his  cases 
shows  that  he  was  working  with  a  less  powerful  wave  than  I  have  used,  for 
no  injury  to  the  middle  ear  parts  occurred.  Hoessli  believed  that  the  one  case 
where  the  wet  cotton  failed  to  protect  was  due  to  the  scratching  lof)se  of  the 
cotton  by  the  animal.  He  followed  this  series  by  one  in  which  he  used  four 
cats,  the  left  ears  stopjied  with  wet  cotton,  the  right  ears  left  open.  To  prevent 
scratching  out  of  the  cotton  the  animals  were  lightly  narcfrtized  and  five  shots 
were  fire<l  at  2^  cm.  above  the  four  of  them.  As  before,  the  animals  were  killed 
24  hours  later.  The  left  ears  in  all  cases  were  normal.  In  three  of  the  four 
right  ears  there  was  an  area  in  the  upjier  part  of  the  basal  turn  (upper  part 
of  second  half-turn)  extending  through  about  15  sections  (thickness  of  sections 
not  stated)  where  a  slight  variation  from  normal  was  found;  the  variation 
consisting  of  a  depression  of  the  organ  of  Corti  in  the  region  of  the  outer 
hair  cells.  The  fourth  case  was  entirely  normal.  In  view  of  the  variations 
in  individual  cases  in  the  longer  series  I  have  used  the  two  exceptions  in  Hoes- 
sli's short  series  are   interesting. 

While  Hoessli  was  interested  primarily  in  the  question  whether  air  or 
bone  conduction  transmits  the  injurious  waves,  he  called  attention  to  the  bear- 
ing of  the  results  with  wet  cotton  to  the  protection  of  soldiers.  All  that  he 
says  of  this  phase  of  it  is  here  quoted  verbatim  :  "Hier  denkt  man  unwill- 
kurlich  an  die  vielen  Falle  von  Schusstrauma  bei  Soldaten,  welche  Watte  in 
den  Ohren  getragen  haben  .sollcn.  \\  ir  sehen  eben  hier,  dass  wenn  der  Wat- 
tepfropf  nicht  ganz  fest  sitzt,  und  am  Ende  gar  niclit  angefeuchtet  ist,  der  Schutz 
des  Ohres  ganz  illusorisch  ist." 

The  region  in  which  the  majority  of  the  lesions  have  occurred  in  my  ma- 
terial is  in  general  the  same  as  was  injured  by  the  various  guns  used  by  Hoshino 
(1917).*  He  exposed  guinea  pigs  to  the  detonations  of  a  medium-sized  re- 
volver, a  hunting  gun,  an  army  rifle,  and  a  cannon.  With  the  small  arms  l)lank 
cartridges  were  used  and  in  most  cases  the  shooting  was  directly  toward  the 
ear,  at  distances  varying  from  "close  up"  to  100  cm.;  two  series  were  run 
with  each  gun.  in  the  first  group  of  series  one  shot  was  fired  toward  each  ear 
of  each  animal,  in  the  second  group  several  shots  each,  the  number  varied  from 
5  to  350.  The  cannon  was  one  used  as  a  "time  piece"  and  was  loaded  with 
only  about  four  pounds  of  powder;  the  animals  were  placed  two  meters  in 
front  of  the  muzzle ;  they  were  blown  as  much  as  twenty  meters  by  the  ex- 
plosion. Two  animals  were  exposed  to  one  shot  each  and  two  to  five  shots 
each.  The  animals  of  the  various  series  were  killed  at  intervals  varying  from 
"immediately"  to  fifty  days  after  exjxisure.  The  greater  number  of  animals 
were  handled  by  an   injection   fixation,   using  Held's    formal-bichromate-acetic 


•It  is  to  be  rejfrcttcH  th.it  the  observations  of  this  Japanese  otologist  are  recorded  in  a  lanKuage 
which  rentiers  them  inaccessible  to  so  many  invcstiRators.  I  desire  to  here  express  my  thanks  to  Dr.  1. 
Wat.inabe.  an   assistant   in  this   laboratory,   for   reading  this  article   to  me. 

14 


mixture.  The  resulting  injuries  to  the  labyrinth  were  more  severe  and  wide- 
spread in  the  cases  where  many  shots  were  fired  than  in  those  "once  exposed" 
(really  twice  since  each  ear  was  considered  separately  in  counting  the  shots),- 
but  were  in  the  same  region  of  the  cochlear  canal  for  each  gun,  whether  one 
or  many  detonations  were  used.  Hoshino  reported  that  the  region  of  most 
severe  injury  varied  for  the  different  guns;  it  was  knvcst  for  the  cannon  and 
highest  for  the  revolver.  The  regions  for  each  were:  (1)  revolver,  second 
turn  and  lower  part  of  third;  (2)  cannon,  upper  part  of  basal  and  lower  part 
of  second  turn;  (3)  army  rifle,  upper  part  of  basal  turn;  and  (4)  hunting 
gun,  lower  part  of  second  turn.  One  monkey  was  used,  it  was  exposed  to  one 
detonation  from  the  rifle  held  close  to  the  ear.  The  injured  area  extended  the 
whole  length  of  the  cochlea  in  this  case,  but  Hoshino  thought  the  wide  extent 
possibly  due  to  the  short  distance  rather  than  to  the  different  type  of  animal. 
The  injuries  to  the  organ  of  Corti  varied  from  minor  atrophic  changes  to  com- 
plete destruction  and  replacement  by  a  simple  epithelium.  Hoshino  also 
broke  the  tympanic  membranes  of  six  animals  and  introduced  staphylococci 
into  the  middle  ears,  waited  until  a  suppurative  otitis  had  developed,  and  then 
exposed  them  to  detonations  from  the  small  arms.  He  found  in  general  the 
same  type  and  extent  of  injuiy  due  to  detonation  as  in  the  animals  with  normal 
middle  ears  similarly  treated.  He  added  this  suppurative  otitis  evidence  in 
support  of  the  view  that  impaired  conducting  apparatus  does  not  protect  the 
labyrinth  from  detonation  injuries.  Hoshino  reported  lesions  involving  the 
tectorial  membrane,  which  was  sometimes  "frayed  out"  and  sometimes  almost 
entirely  missing.  While  the  technic  used  on  my  material  is  not  favorable  for 
the  study  of  the  tectorial  membrane,  because  of  the  way  it  is  shrunken  and  fre- 
quently turned  up  even  in  normal  cases,  I  have  observed  no  evidence  that  it  has 
definite  lesions  due  to  detonations.  \\'hile  Hoshino  stated  that  the  area  injured 
was  more  extensive  with  repeated  detonations  than  with  one,  he  did  not  men- 
tion variations  in  extent  under  identical  conditions,  such  as  my  material  shows. 
The  small  amount  of  powder  used  in  the  cannon  and  the  fact  that  no  shell 
was.  used  would  indicate  that  the  intensity  of  the  detonation  was  not  so  great 
as  that  of  the  majority  of  artillery  pieces  and  exploding  shells,  but  the  plac- 
ing of  the  animals  in  front  of  the  muzzle  where  they  were  hurled  twenty  me- 
ters by  the  explosion  simulated  to  a  degree  the  conditions  in  the  battle  field 
where  men  are  frequently  hurled  by  the  blast  of  an  exploding  shell  and  at  the 
same  time  exposed  to  the  intense  sound.  It  is  of  interest  to  note  that  the 
lesions  produced  by  Hoshino's  cannon  were  of  the  same  nature  as  those  pro- 
duced by  the  smaller  detonations  of  both  himself  and  others;  this  indicates 
that  the  study  of  lesions  due  to  relatively  small  detonations  are  of  value  in 
interpreting  the  effects  of  more  intense  explosions. 

Prenant  and  Castex  (1916)  placed  animals  in  cages  near  large  caliber 
guns  at  Fontainel)leau.  In  no  case  was  the  tympanic  membrane  ruptured  or 
the  middle  ear  inflamed ;  ten  guinea  pigs  and  six  rabbits  were  used.  The 
preservation  of  the  labyrinths  was  poor;  they  reported  extensive  cochlear 
Jesions  of  the  type  to  l)c  expected  from  previous  work  in  this  line  with  smaller 

15 


guns.  Since  tliis  is  the  only  work  in  which  animal  ccKhlcie  have  been  re- 
l>(jrtcd  after  exposure  to  detonations  of  such  large  guns  as  they  used,  it  is 
very  much  to  be  regretted  that  the  histoh)gic  teclinic  used  gave  such  poor 
resuhs,  for  this  makes  them  of  very  httle  vahie  except  for  very  indefinite 
comparisons  and  conclusions. 

The  report  of  J.  S.  and  John  Fraser  (1917),  made  upon  autopsy  ma- 
terial from  soldiers  deafened  by  detonations,  must  be  considered  in  the  light 
of  the  histologic  tcchnic  employed  by  them,  which  was  such  as  to  render  the 
results  very  indefinite,  as  they  realized.  Hemorrhage  into  the  labyrinth  and 
about  the  entrance  of  the  nerve  roots  in  the  fundus  of  the  internal  meatus 
were  definite  findings  of  interest.  It  is  almost  imjKJSsible  in  their  material 
to  differentiate  the  artefacts  from  the  actual  lesions  in  the  organ  of  Corti  and 
nervous  tissues.  Wilson  reported  recently  (Journal  of  the  American  Medical 
Associatidn,  August  24,  1918)  the  condition  of  a  temporal  bone  secured  at 
autopsy  six  hours  after  the  death  of  a  soldier  who  had  l>een  deafened  by  a 
shell  explosion.  (Wilson  said  that  two  were  reported  in  the  Harvey  lecture 
which  he  gave;  but  this  is  not  yet  available  to  me.)  Formalin  fixation  was 
used.  He,  like  Fraser,  reported  hemorrhage  in  the  base  of  the  internal  auditor}' 
meatus.  There  was  \cv\  evident  damage  to  the  cochlear  parts ;  edema  and 
small  cell  infiltration  were  mentioned  as  l)eing  present  in  the  ganglion,  stria 
vascularis,  basilar  membrane  and  organ  of  Corti.  The  epithelial  cells  and  the 
ganglion  cells  were  "indistinct,"  doubtless  due  in  part,  at  least,  to  the  time  after 
death  before  placed  in  fixative  and  to  the  necessarily  slow  penetration  of  the 
fixative,  even  though  the  superior  semicircular  canal  was  opened. 

The  presence  in  my  material,  except  in  the  most  severe  injuries,  and  also 
in  Hoessli's  detonation  cases,  of  the  inner  hair  cells  is  interesting  in  connec- 
tion with  Hoessli's  observations  on  injurv'  by  the  sound  from  organ  pipes ;  he 
found  the  inner  hair  cells  intact  after  the  outer  hair  cells  had  disappeared  and 
even  sometimes  when  the  supporting  apparatus  of  the  outer  hair  cells  had  broken 
down.  These  facts  indicate  either  that  the  inner  hair  cells  are  more  resistant 
to  injurious  sound  waves,  or  that  they  do  not  receive  as  great  intensity  of 
the  waves  as  do  the  outer  hair  cells.  This  is  not  taken  into  account  in  any 
of  the  theories  of  hearing.  The  statement  of  Shambaugh  (1911)  that  the  ciliae 
of  the  outer  hair  cells  are  in  constant  contact  with  the  tectorial  membrane 
while  those  of  the  inner  hair  cells  are  free  is  suggestive  in  this  connection. 

None  of  the  reports  of  previous  experimental  work  involving  detonation 
injury  of  the  cochlea  make  any  mention  of  separated  zonal  lesions,  which  are 
so  plentiful  in  my  material.  (See,  for  example,  "34  Rt."  in  Chart  I.)  It  is 
evident  that  if  the  variations  in  sound  waves  are  perceived  by  any  type  of 
perij)heral  analysis,  the  occurrence  of  definite  zones  of  injury  to  the  organ  of 
Corti  indicates  that  the  parts  injured  were  most  active  in  converting  the  sound 
waves  into  nervous  energy.  In  other  words,  if  either  the  Helmholtz  theory 
in  its  original  form  or  in  any  of  its  modifications,  or  the  Lehmann  or  the 
Kwald  or  the  Kohier  theory,  or  the  theories  involving  the  tectorial  membrane 
as  a  differentiating  mechanism,  are  correct,  injured  zones  of  the  organ  of  Corti 

16 


are  to  be  interpreted  as  being  in  the  areas  of  resonance  for  the  sound  waves 
that  caused  the  damage.  If  there  is  any  definite  pitch,  or  if  there  is  a  mixture 
of  vibration  frequencies  in  the  sound  waves  produced  by  the  firing  of  a  45 
caHber  pistol,  it  seems  reasonable  to  suppose  that  it  will  not  vary  with  dif- 
ferent shots  to  the  extent  that  would  cause  the  difference  in  cochlear  lesions 
observed  under  otherwise  identical  conditions;  that  is,  open  ears  at  the  same 
distance  and  direction  from  the  gun.  No  attempt  has  been  made  to  obtain 
and  analyze  sound  curves  from  the  detonations  used,  so  that  no  conclusions  can 
be  reached  along  this  line. 

A  general  view*  of  Chart  I,  in  which  are  presented  the  cochlear  conditions 
in  the  open  ears  exposed  to  the  firing  of  one  shot  at  15  cm.  from  the  muzzle 
of  a  45  caliber  Colt  automatic  pistol,  reveals  that  the  average  center  of  the 
injured  areas,  other  than  isolated  sections  of  first  degree  injury,  is  in  the  third 
half-turn,  except  for  the  few  cases  with  severe  injury  in  the  vestibular  part 
and  first  half-turn.  The  making  of  the  charts  with  the  relative  lengths  of  the 
half-turns  indicated  permits  the  ready  recognition  of  the  fact  that  the  center 
of  the  total  length  of  the  cochlear  duct  of  the  guinea  pig  is  also  in  the  third 
half-turn.  In  Chart  III,  in  which  are  presented  the  cochlear  conditions  in 
the  "protected"  ears,  the  average  center  of  the  injured  areas  is  somewhat  higher; 
and  there  is  almost  complete  absence  of  injtuMes,  even  of  the  first  degree  in 
isolated  sections,  in  the  whole  of  the  basal  turn  (vestibular  part  and  first  and 
second  half -turns)  of  all  the  cochleae,  except  those  in  the  Elliott  and  W'ilson- 
Michehon  series. 

These  observations  of  separated  zones  of  injury  and  the  average  grouping 
of  the  same  are  presented  and  attention  called  to  them  in  the  hope  that  they 
may  prove  of  value  at  some  time,  in  connection  with  other  data,  in  solution 
of  the  problem  of  the  physiolog}'  of  hearing. 

It  is  a  pleasure  to  express  here  my  appreciation  of  the  valuable  sugges- 
tions made  by  my  chief.  Dr.  Huber,  during  the  course  of  this  work. 

RESUME  OF   ALL   MY   REPORTS   UPON    WAR  DEAFNESS   AND   ITS    PREVENTION 

1.  Laboratory  methods  for  the  testing  of  measures  for  the  prevention  of 
detonation  injuries  to  the  ear  have  been  devised  and  such  tests  have  been 
carried  out  upon  various  protective  measures. 

2.  These  tests  indicate  that  the  measures  tested  may  be  divided  into  tvvO' 
definite  groups  upon  the  basis  of  their  efficiency  in  preventing  the  passage  of 
the  force  of  the  detonation  waves  used ;  the  variations  within  each  group  are 
less  decisive.  In  the  more  efficient  group  are  the  Scientific  Ear  Drum  Pro- 
tector "Tommy,"'  the  Mallock-Armstrong  Ear  Defender,  cotton  soaked  with 
glycerine,  cotton  soaked  with  vaseline,  and  the  wax  cone  of  the  It:dian  navy 
type.  In  the  less  efficient  group  are  dry  cotton,  the  Elliott  Perfect  Ear  Pro- 
tector, and  the  Wilson-Michelson  device. 

3.  The  cochlear  lesions  produced  by  the  detonations  differ  in  extent  and 
distribution  from  those  hitherto  reported;  the  injur\'  areas  are  frequently  sep- 
arated by  normal  zones;  these  lesions  are  recorded  in  a  graphic   form  which 

17 


makes  them  more  available  for  reference  Ihan  if  the  usual  method  of  written 
I)rotoc(»ls  had  been  followed.  The  facts  are  |ircsentcd  without  drawini:^  theo- 
retical conclusions  as  to  their  bearing  on   tiie  i)hysiolopy  of  hearing. 

ItIIlUIOGK.\ril\ 

(Only  tlioM-  artick-^  mciitinned   in   this   rtjiort   oi    ;Ik   muro^coiiR-   (•Miinin.itKin   of  the 
labyrinths  arc  hsted.) 

Frascr,   J.    S..   and    Frascr,   John:      The    Morbid    .Anatomy   of    War    Injuries   of   the    Ear, 

Proc.   Roy.    Soc.   Med.,   x,  Otol.   sect.,   1917,  56-90.      (This  later  appeared   also  in  the 

Jour.   Laryngol.,  etc.,   Nov.  and   Dec,   1917  numbers.) 
Hoessli,  H.:     Wciterc  expcrimcntclle  Studicn  libcr  die  .Akustische  Schadigung  des  Sauge- 

ticrlabyrinths.  Ztschr.   f.  Ohrenh..  1917,  Ixiv,   101-145. 
Hoshino,  T. :     [.\ti  Experimental   Study  of  the  Pathology  of  Ears  Injured  by  Sound  and 

a  Consideration  of  the  Physioloijic  Bearing  of  the  Results],  1917.    Kyoto  Igaku  Zassi, 

xiv.     (Xinety-seven  pp.  with  63  figures.) 
Meyer:     Das  akustische  Trauma,  .\rch.  t.  Ohrenh.,  1915,  xcviii,  152-157. 
Prcnant   and   Castex :      Recherches   expcrimentales   et   histologiques    sur    la   commotion    du 

labyrinthe.   1916,  Bull.  .\cad.  de   Med.,  3s.,  Ixxvi,  535-537.     (A  more  detailed  account 

api)earcd  later  in  the  Paris  Medicale,   March  8,   1917.) 
Shambaugh,    G.    E. :      Das    Verhaltnis    zwischen    Membrana    tectoria    und    dem    Cortischen 

Organ.  Ztschr.  f.  Ohrenh.,  1911.  Ixii,  235-240. 
Wilson,  J.  G. :     The  Effects  of  High  Explosives  on  the  Ear,  Jour.  .\m.  Med.  .\ssn.,  Aug. 

24.  1918. 
Wittmaack,  K. :     t^ber  Schadigung  dcs  Gehors  durch  Schalleinwirkning,  Ztschr.  f.  Ohrenh., 

1907.  liv,  37-80. 
Yoshii,  U. :     1909.     Experimcntelle  Untersuchungen  iiber  die  Schadigung  des  Gehorsorgan 

durch   Schalleinwirkung.   1909;  ibid.,  Iviii,  201-251. 


18 


Explanation  of  Figures 

ABBREVIATIONS 

a.,    Apical  end  of  ductus  cochlearis. 

c.C,    Cells  of   Claudius. 

c.D.c,    Cuticular  processes  of  Deiters'  cells    (basal  part). 

c-H.,    Cells  of  Hensen. 

ci.s.,    Cells   of   internal   spiral   sulcus. 

f.r.,     Membrana  tympani   secundaria  closing  the   fenestra  rotunda. 

g.sp;     Ganglion   spirale. 

i.h.c,    Inner  hair  cells. 

x.p.,    Inner   pillars. 

I.O.,     Lamina  spiralis  ossea. 

l.sp.,     Spiral  ligament. 

m.h.,    Basilar  membrane. 

m.rct.,    Membrana   reticularis. 

m.v.,     Membrana    vestibularis    (of    ReissnerV 

«.,    Nerve  fibers  in  the  spiial  osseous  lamina. 

n.c.    Cochlear  nerve. 

n.D.c,    Nuclei  of  Deiters'  cells. 

n.o.p.,    Nuclei  of  the  outer  pillar  cells. 

N.S.,    Nuel's  space. 

o.h.c,   Outer  hair  cells. 

o.h.cA,     Outer  hair  cells  of  the  first  row. 

o-h.c.2,    Outer  hair  cells  of  the  second  row. 

o.h.c.3,     Outer  hair  cells  of  the  third  row. 

o.p.,    Outer   pillars. 

o.t.s..     Outer  tunnel  space. 

ph.pr.,    Phalangeal   processes   of   Deiters'   cells. 

sac,    Sacculus. 

s.t.,     Scala  tympani. 

S.V..     Scala  vestibuli. 

t.f.,   Tunnel  nerve  fibers. 

t.s.,    Tunnel  space  of  the  organ  of  Corti. 

utr.,   Utriculus. 

v.p.,    "Vestibular  part"  of  the  ductus  cochlearis. 

v.sp.,  Vas  spirale. 


19 


Legends  for  Plate  I 

Fig.  1. — Outline  drawing  of  a  mid-modiolar  section  of  a  left  cochlea  of  a  guinea  pig. 
Guinea  pig  55.  left  cochlea,  slide  1,  row  4,  section  1,  15^.  The  arabic  numerals  in  the 
various  sections  of  the  ductus  cochlearis  indicate  the  designation  of  half -turns  as  used  in 
this  article.  The  part  in  the  modiolar  section  is  considered  as  the  center  of  each  half-turn; 
the  junctions  of  the  half-turns  are  in  the  sections  which  cut  the  curve  of  the  organ  of  Corti 
tangentially. 

Fic.  2. — Outline  drawing  of  a  section  of  a  right  cochlea  of  a  guinea  pig  to  one  side  of 
the  modiolar  axis,  showing  the  position  of  what  has  been  termed  the  "vestibular  part" 
of  the  ductus  cochlearis  and  the  relations  of  parts  in  "oblique"  and  "tangential"  sections. 
Arabic  numerals  as  in  Fig.  1.     Guinea  pig  21,  right  cochlea,  slide  2,  row  1,  section  2,  15x. 

Figs.  3  to  14,  inclusive,  were  drawn  with  the  aid  of  a  camera  lucida  at  a  magnifica- 
tion of  885  diameters,  and  have  been  reduced  in  reproduction  to  295  diameters,  one-third 
of  the  original  size  of  the  drawing.  Being  at  the  same  magnification,  comparison  is  facil- 
itated. Figs.  3,  4,  and  12  are  drawings  of  sections  of  the  organ  of  Corti  in  normal  condition, 
and  are  presented  for  comparison  with  the  ones  having  lesions.  All  the  cochleae  were 
prepared  by  the  same  tcchnic  and  the  sections  used  for  illustrations  were  selected  to 
present  the  typical  lesions  observed.  See  the  text  matter  for  the  technic  and  the  terminology 
used   in   designating  the   lesions. 

Fig.  3. — Drawing  of  a  normal  organ  of  Corti  in  radial  section.  Guinea  pig  21,  right 
cochlea,  slide  1,  row  4,  section  8,  second  half-turn,  295x.  As  is  well  known,  the  shape  of  the 
organ  of  Corti  varies  in  the  diflferent  parts  of  the  ductus  cochlearis;  allowance  must 
be  made  for  this  in  comparing  this  drawing  with  those  of  lesions  in  other  parts  of  the  cochlea. 

Fig.  4. — Drawing  of  a  normal  organ  of  Corti  in  oblique  section.  Guinea  pig  41.  right 
cochlea,  slide  1,  row  5,  section  2,  second  half-turn,  295'<. 


20 


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Plate  I. 


21 


Legends  for  Plate  II 

FiC.  5. — Organ  of  Corti,  with  first  degree  injury,  radial  section.  Guinea  pig  52,  left 
cochlea,  1-4-7.  tliini  li:ilf-turn,  2Q.S<.  The  outer  liair  cells  of  the  second  and  third  rows  are 
missing. 

Fig.  6. — Organ  of  Corti,  with  first  degree  injury,  radial  section.  Guinea  pig  30.  left 
cochlea,  1-6-2,  first  half-turn,  295x.  The  outer  hair  cell  of  the  first  row  is  absent,  and  the 
nucleus  of  the  corresponding  Deiters'  cell  is  displaced  downwards. 

Fig.  7. — Organ  of  Corti,  with  first  degree  injury,  oblique  section.  Guinea  pig  47, 
right  cochlea,  1-5-5,  second  half-turn,  295x.  Compare  with  Fig.  4.  Some  of  the  cells  of 
each  row  of  outer  hair  cells  arc  missing. 

Fig.  8. — Organ  of  Corti,  with  second  degree  injury,  radial  section.  Guinea  pig  40, 
left  cochlea,  1-3-2,  fourth  half-turn,  295x.  All  the  outer  hair  cells  are  missing  and  the 
Deiters'  cells  are  partially  destroyed.  Xote  that  the  general  shape  of  the  organ  is  retained; 
it  is  different  from  that  of  Fig.  3,  but  is  the  normal  outline  for  this  part  of  the  cochlea. 

Fic.  9. — Organ  of  Corti.  with  third  degree  injury,  radial  section.  Guinea  pig  29,  left 
cochlea,  1-3-6,  fourth  half-turn,  295^.  The  shape  of  the  organ  is  lost,  being  crushed;  there  is 
cellular  debris  in  the  spaces  of  the  organ;  the  outer  hair  cells  are  missing;  the  reticular 
membrane  in  this  case  is  broken  and  pieces  of  it  are  seen  scattered  through  the  mass. 

Fig.  10. — Organ  of  Corti,  with  fourth  degree  injury,  radial  section.  Guinea  pig  28, 
left  cochlea,  1-4-2,  third  half-turn,  295>^.  The  severity  of  this  type  of  lesion  may  be  seen 
at  a  glance;  all  the  essential  parts  of  the  organ  of  Corti  have  been  destroyed.  Adhering 
to  the  scala  tympani  surface  of  the  basilar  membrane  may  be  seen  two  red  blood  cells  and 
one  leucocyte ;  this  is  one  of  the  few  cases  where  even  this  much  hemorrhage  was  observed. 

Fig.  11 — Drawing  of  a  section  in  which  the  organ  of  Corti  has  been  almost  entirely 
replaced  in  48  hours  by  a  simple  epithelium.  Guinea  pig  50,  left  cochlea,  1-4-9,  third  half- 
turn,  295*^.  This  is  the  only  instance  in  my  material  in  which  the  destruction  is  so  complete. 
I  have  not  given  it  a  designation  of  degree  as  was  done  with  the  types  of  lesions  which 
occurred  often. 


')■) 


23 


Legends  for  Plate  III 

Figs.  12,  13.  and  14  sliould  be  compared  directly  in  order  to  interpret  readily  the  lesions 
shown  in  13  and  14.  .\11  three  are  drawings  of  sections  which  have  been  selected  as  being 
of  corresponding  p.nrts  of  tlic  various  organs  of  Corti.  The  elements  of  the  organ  of  Corti 
have  been  labelled  in  Fig.  12  only;  reference  should  be  made  to  it  in  studying  Figs.  13  and  14. 
Oblique  and  tangential  sections  are  favorable  for  observing  lesions  because  of  the  number  of 
each  element  present  in  a  single  section. 

Fig.  12. — Normal  organ  of  Corti  in  tangential  section;  the  plane  of  section  is  parallel 
to  the  modiolar  exis.  Guinea  pig  33,  left  cochlea,  1-5-6,  junction  of  fourth  and  fifth  half- 
turns,  295  ■<. 

Fig.  13. — Organ  of  Corti  with  first  degree  injury,  tangential  section.  Guinea  pig  27,  left 
cochlea,  1-5-2.  junction  of  fourth  and  fifth  half-turns,  295x.  When  compared  with  Figs.  5 
and  6,  which  are  of  radial  sections  of  the  organ  of  Corti,  the  nature  of  this  lesion  is  better 
understood ;  a  few  or  even  single  outer  hair  cells  are  missing  in  a  place,  ijuch  lesions  are 
not  artefacts  due  to  the  dropping  out  of  bits  of  the  tissue  during  or  after  the  sectioning, 
since  the  pieces  are  embedded  in  celloidin  and  there  is  no  evidence  of  such  vacancies  in  the 
celloidin,  which  is  itself  faintly  stained  and  would  therefore  show  gaps. 

Fig.  14. — Organ  of  Corti,  with  fourth  degree  injury,  tangential  section.  Guinea  pig 
28,  left  cochlea.  1-2-7,  junction  of  third  and  fourth  half-turns  295x.  Compare  with  Fig.  10, 
which  is  of  this  type  of  lesion  in  radial  section.  Comparison  with  Fig.  12  emphasizes  how 
much    destruction    has   occurred. 


24 


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Lopcnd   for  Plate  I\' 

{Sec   I^Ojfcs    JO    and    J7.) 

For  the  explanation  of  the  general  plan  of  the  charts  and  of  the  s>'mbols  used,  see 
the  text  matter,  page  7,  and  the  preceding  description  of  legions.  The  numhers  in  pa- 
rentheses refer  to  the  notes  given  in  the  legends  for  the  individual  charts. 

Chart  I. — A  grapliic  presentation  of  the  condition  of  the  organ  of  Corti  in  the 
cochlea?  of  ears  which  were  entirely  open  when  exposed  to  the  detonation  produced  by  one 
shot  from  a  45  caliber  Colt  automatic  pistol,  fired  with  the  muzzle  at  15  cm.,  measured  from 
the  opposite  ear,  the  barrel  pointing  downward  about  20  degrees  from  the  horizontal  from 
above  and  in  front  of  the  animal  along  the  left  side. 

Chart  il. — .\  graphic  presentation  of  the  condition  of  the  organ  of  Corti  in  the  cochleae 
of  the  ears  which  had  the  open  rubber  ear  and  a  glass  tube,  of  the  dimensions  given  in  the 
chart  for  each  case,  placed  in  the  usual  way.  With  the  2.0  mm.  tube,  examination  of  the 
wax  packing  after  the  shooting  showed  the  presence  of  wax  in  the  end  of  the  tube  with' 
animals  47  and  42.     (Cf.  Table  II  of  the  middle  ear  report.) 

Chart  III. — .\  graphic  presentation  of  the  condition  of  the  organ  of  Corti  in  the 
cochleae  of  the  ears  which  were  protected  by  the  methods  indicated.  These  are  left  cochleae 
in  every  case,  and  the  position  of  the  gun  was  tiiat  given  in  the  legend  for  Chart  1,  except 
that  the  distance  was  measured  from  the  protected  ear. 

(1)  (Animal  56)  The  fixation  of  these  turns  is  too  poor  for  one  to  be  certain  as  to 
possible  injuries  of  limited  extent,  there  are  none  of   large  extent. 

(2)  (Animal  53)  The  fixation  is  so  poor  that  the  sections  arc  worthless  for  the 
determination  of  detonation  injuries. 

(3)  (.Animal  30)  The  apex  of  this  cochlea  was  accidentally  crushed  during  its 
removal;  the  resulting  gross  distortion  is  too  great  for  one  to  be  certain  of  the  condition 
of  the  organ  of  Corti  in  these  apical  turns. 

Chart  IV. — A  graphic  presentation  of  the  condition  of  the  organ  of  Corti  in  the 
cochlejE  of  ears  which  were  entirely  open  when  exposed  to  detonations  from  a  45  caliber 
Colt  automatic  pistol  with  other  than  the  usual  arrangement  (see  legend  to  Chart  I). 
The  distance  from  the  muzzle  and  the  number  of  shots  fired  are  indicated  in  the  chart  for 
each  case.  For  the  more  exact  position  of  the  gun  eacii  time,  reference  may  be  made  to 
Table  1  of  the  middle  ear  report. 

(1)  (.Animal  18,  right  cochlea)  The  fixTition  is  too  poor  for  one  to  be  certain  of  more 
than  the  general  condition;  tlierc  may  be  other  areas  of  injury  of  small  extent,  but  there 
are  no  other  extensive  injured  zones. 

(2)  (.Animal  18,  left  cochlea)  This  cochlea  was  not  entirely  sectioned  because  of 
poor  decalcification;  the  areas  blocked  ofT  are  those  not  sectioned;  their  condition  is 
accordingly  iiiikiiouii. 

I'l'BLiSMKK  s  .XiiTi.  Tlie  cxact  distribution  of  the  fourth  degree  injury  <loes  not  show 
clearly  in  these  charts  as  printed,  owing  to  the  lack  of  differentiation  of  the  intermediate 
and  dark  grays. 


28 


1 


Gaylord  liros. 

Makers 

Syracuse,  N.  Y 

PAT.  JAN,  21,1908 


392638      '^'PZ5o 


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